New York — When the World Trade Center collapsed after a terrorist attack on Sept. 11, 2001, it exposed hundreds of thousands of people to known and suspected carcinogens. The air was filled with dust, debris and toxic emissions.

Since that time researchers with the World Trade Center Health Registry have tracked almost 5,600 people who may have been in the area – rescue and recovery workers and residents and visitors to Lower Manhattan – to monitor their emotional and physical health, including any incidents of cancer. The registry compares cancers and other illnesses in the World Trade Center group with typical cancer rates for New York City dwellers.

"We know that there were exposures to cancer causing agents from 9/11, and that's certainly a serious public health concern," said Steven D. Stellman, Ph.D., M.P.H. of the New York City Department of Health and Mental Hygiene.

"In both the rescue-recovery workers and the non-rescue recovery workers we did not find any different overall cancer rate from what we determined from the background rate from the New York state cancer registry," he said. 

In a study published in the Journal of the American Medical Association, the group noted that rescue-recovery workers had a significantly increased rate of three types of cancer: prostate, thyroid and myeloma, a blood cancer.

Researchers say rates of prostate and thyroid cancers were also elevated in a recent study involving New York City firefighters.

They say cancer is fundamentally different from many other 9/11-related diseases. 

"Most solid tumors have a very long latency period and many don't appear for many years or decades after the initial exposure," Stellman pointed out.

The researchers will continue to track those who lived and worked in Lower Manhattan, and they are planning a third and fourth round of cancer surveys through the registry's active referral program.